A 19-year-old Oxon Hill woman whose 2-month-old son was found dead last fall in woods near her home was sentenced yesterday to 30 years in prison after pleading guilty to second-degree murder in Prince George's County Circuit Court.

Edith Yvonne Newton, who police said smothered her crying infant, David Anthony Newton, on Aug. 23 and hid his body in the trunk of her car for several days, was charged a week later with first-degree murder after she led police to the body.

Under a plea agreement between defense attorneys and prosecutors, Judge Audrey Melbourne recommended that Newton be evaluated for incarceration and treatment at the Patuxent Institution in Jessup, Md., where psychiatric treatment and rehabilitation programs are stressed. If Newton is admitted there, her attorney said last night, the 30-year sentence will be replaced by an indeterminate term.

Defense attorney Herbert Levenstein described his client after the court proceedings as "a young lady who's never been in trouble in her life. She's from a good family, she's well-educated . . . but she was under tremendous pressure from a multitude of sources" at the time of her child's death.

Newton had been attending Prince George's Community College, but was forced to drop out to care for her son, Levenstein said. She was living with her parents at the time of the baby's death, and had explained the child's absence by saying he was staying with relatives.

Police began investigating the baby's disappearance after an anonymous phone tip to the county Department of Social Services. Newton first told police the baby was missing, but eventually led officers to his body.